Standard solid-phase immunoassays with antibodies involve the formation of a complex between an antibody adsorbed/immobilized on a solid phase (capture antibody), the antigen, and an antibody to another epitope of the antigen conjugated with an enzyme or detectable label (tracer antibody). In the assay, a sandwich is formed: solid phase/capture antibody/antigen/tracer antibody. In the reaction catalyzed by the sandwich among other things the activity of the antibody-conjugated enzyme is proportional to the antigen concentration in the incubation medium. Anti-idiotypic antibody assays are mentioned, for example, in U.S. Pat. No. 5,219,730; WO 87/002778; EP 0 139 389; and EP 0 170 302. Wadhwa, M., et al. (J. Immunol. Methods 278 (2003) 1-17) report strategies for the detection, measurement and characterization of unwanted antibodies induced by therapeutic biologicals. A method for producing anti idiotypic antibodies is reported in EP 1 917 854.
In WO 2008/119353 bispecific antibodies and methods for producing thereof are reported. Methods for determining the bivalency of protein and antibody therapeutics are reported in WO 2006/096697. In WO 2008/134046 potent, stable and non-immunosuppressive anti-CD4 antibodies are reported. Muller, K. M., et al. report that the first constant domain (CH1 and CL) of an antibody can be used as heterodimerization domain for bispecific miniantibodies.